


Instruct

by Undertale_Writing_Challenges



Category: Undertale (Video Game)
Genre: BECAUSE SKELETONS CAN HAVE SEX, D/s, Dom/sub relationship, ECTO BITCH, Ecto-Genitalia (Undertale), Ecto-Penis (Undertale), Ecto-Tongue (Undertale), Ecto-Vagina (Undertale), FELL EATS RED OUT, Fell Paps is a Sadist, Fell is a megalomaniac, Fontcest, I Will Go Down With This Ship, I'm Going to Hell, Incest, LITERALLY, M/M, No Plot/Plotless, Orgasm Denial, Plot What Plot/Porn Without Plot, Red is an obedient pet, Sibling Incest, Skeletons Fucking, Sorry Not Sorry, Spoiler Alert - Freeform, WE ARE ALL SINNERS HERE!, YOU DON'T KNOW WHAT HAPPENS BEHIND CLOSED DOORS, all the pov switches, ammirite, and fell sans is a masochist what a surprise, and you're coming with me, cocktease, ecto, fuck it, i fucking teased the ending again, megalovaniac, red finally gets to fucking come, shut up, that's what my life has come to, the author switches povs so many times so frequently it makes it confusing, this is just porn, tra la la beware the woman who is bad at tagging, wow there still isn't any penetration, yeY part two, yep
Language: English
Status: Completed
Published: 2017-05-11
Updated: 2017-05-26
Packaged: 2018-10-30 12:38:39
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 2,110
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10876953
Author URL: https://archiveofourown.org/users/Undertale_Writing_Challenges/pseuds/Undertale_Writing_Challenges
Summary: "He looked up at Papyrus, one eye screwed shut and the other half-lidded, his tongue hanging out and covered in sticky cum. His thumb came down to his cheek, swiping across it and dragging more of his release into Sans' mouth.'Good boy.'"Full fic of 'Instruct' over on my Fontcest Dictionary Challenge!





	1. Chapter 1

**Author's Note:**

> huhhh i wanted to write this anyways.
> 
> Gotta give a shout out to the anon Apple+Curry for giving me the idea of writing Sans' reward *eyebrow wiggle* Good boys deserve rewards after all!

There was no question that Boss was a megalomaniac. He loved to order others around, terrifying people with his strength and position. Sans, of course, was no exception.

It didn't matter what the command, it didn't matter how tedious or how seemingly unimportant, Sans would drop whatever he may have been doing to please his Boss. It didn't matter if he was told to do the laundry, clean his room, or...

Go to Boss' room, close the door, strip, and wait.

Simple things, really.

He'd been standing in the dark room (because pets aren't allowed on the bed unless they're invited) alone, naked  ~~and fucking horny~~ for what felt like an hour. His magic had long since formed unbidden in his pelvis, the slickness of his own excitement running down his femurs  ~~and dripping on the floor.~~ He aches to slip a hand between his legs, to fuck himself silly with one of Boss' toys, to fucking hump a pillow at this point. But Boss didn't say he could touch himself, so he doesn't. He's a good boy. A good boy that can control himself for his master.

His control nearly back flips out the window at the sound of Boss' boots heading heavy up the stairs. He hears a noise, and it takes him a moment to realize that he hears himself whimpering. Boss hasn't touched him, hasn't even looked at him, and he's a mess. 

The door opens with a creak and Sans straightens his posture as much as possible, despite quivering from head to toe. 

The first thing he notices about Papyrus is he's shed his armor, leaving only the black tank behind. The second thing is that his soul is glowing bright enough to show it's brilliant red through the dark fabric. And the third, he notices as his gaze trails down. Papyrus is hard, and seemingly has been for a while as there's a wet spot gathering on his dark pants.

He doesn't speak. He just takes slow strides towards Sans, fiddling with his pants. Sans' eyes are glued to his hands, watching as they free that beautiful cock that he's been fantasizing about for the last --  _Stars_ knows how long. He stops once he's right in front of Sans, both in silence. Sans  ~~not so~~ patiently waiting for a command, and Papyrus toying with his brother's self-control. 

"On your knees." The command was sharp, crisp, and left no room for argument.

Sans found himself involuntarily level with his brother's dick. It's almost embarrassing how much power Papyrus holds over him, body already snapping to attention at any order that comes from him. He'd be lost without his Boss.

The softest of grunts came from Papyrus' mouth as he jerked himself at a rapid pace. Sans' mouth watered at the sight, tongue forming unbidden and heavy. But he stayed still, he didn't move because Boss didn't say to, he didn't touch him no matter how much his hands were itching to.

"Open." And he did, just in time for his Boss' release to splatter thick across his tongue and his face.

He looked up at Papyrus, one eye screwed shut and the other half-lidded, his tongue hanging out and covered in sticky cum. His thumb came down to his cheek, swiping across it and dragging more of his release into Sans' mouth.

"Good boy." 

Sans draws his tongue back into his mouth, moaning as the sticky-sweet taste of his brother slides down his throat. Papyrus responds with his own possessive growl. "On the bed." 

Sans scrambles to comply, sitting on the edge of the bed and staring up at his brother. Papyrus leans over him, causing him to move backwards, ending up half on the bed and half hanging off. "You've been such a good boy," he praises as he nuzzles into Sans' collarbone. "Such a patient pet."

Sans nearly lurches as Papyrus licks a trail down his sternum. He's biting, licking, nibbling his way down Sans' body and it's making his toes curl as he purposely hits all his sensitive spots. "Good boys deserve a reward, right?"

The way he said it, the direction he was heading... Stars, Boss would never, boss never gives head, boss never--

Sans can't help but scream as Papyrus' long tongue pushes it's way inside of him. It's almost like a tentacle, wriggling and pressing against all his hot spots at once. His toes curl and his back arches and  _Gods he's close already._ Papyrus just started touching him and he's already writhing in ecstasy.

But he drags it out because it's rare for Papyrus to reward him, and he doesn't want it to end just yet. But,  _stars_ , it's so tempting to just let go and submit to the pleasure. Submit to his Boss.

"b-boss~" his name tumbles out of his mouth, and he feels the deep growl he gets in response vibrate across his swollen lips "b-boss i'm c-close," he's surprised he can still string words together at this point, his mind is so clouded with lust.

Papyrus is quick to react, tongue slithering out in favor of swirling around the swollen nub, two fingers slamming into his opening to the hilt. 

"fuck! boss! m'gonna- m'gonna come, please, please can i come, can i come,  _boss, please._ " he's babbling and he knows it, but he wants to come so bad but he needs his Boss' permission.

And just like that, Papyrus stops, fingers withdrawing as he stares deviously up at his brother. Sans can feel his peak slipping away and  _he just needed a little more friction._

"I didn't say you could come, did I?" Papyrus stands, leaving Sans breathless against the sheets, expression twisted into something that he knows just screams  _What the fuck?_ "I have some errands to run. Stay here until I get back," 

"And if you're good, maybe I'll let you come."


	2. oh look the author continued this mess

**Summary for the Chapter:**

> oh look the author continued this mess

**Notes for the Chapter:**

> oh look the author continued -- okay the joke's stale.
> 
> There's been a part two floating around in my drafts since I posted this oneshot.

He honestly couldn't believe Boss had done this. Sure. Papyrus has edged him before. A lot. Sure, Papyrus has strapped vibrators to him on a setting that keeps him just on the edge, not giving him enough stimulation to topple over. But he can't recall a time Papyrus actually  _left_ the house, leaving Sans to grind hopelessly into the air, desperate for more friction. Not only that,  _he didn't tie him down._ He's free, completely able to reach down and end his torture, but he  _can't_ because Boss said he  _couldn't._ So his hands scratched marks into the headboard behind him as he clutched it in a desperate attempt to not touch himself. 

His thoughts are clouded, his own whines and whimpers sound pathetic to his own (lack of) ears. He's wrecked and he's desperate, the only thing he's able to think about is release and  _how unfair this is._

* * *

He wonders if he should try making Sans a quiche...

It's not as if Papyrus didn't really have things to do. Going to the store  _definitely_ couldn't have waited. And he  _totally_ had to walk all the way to the Capitol because the shop in Snowdin is of poor quality. And he  _needed_ to walk all the way to the Capitol because he doesn't have the fare for a boat ride.

Okay, fine, he's just killing a couple of hours.

Papyrus should feel bad for doing this to Sans. He really should. It's cruel, and sadistic. And that's why he doesn't feel bad. Instead, he's incredibly turned on at the thought of his brother squirming on his bed, begging for his Boss, his Master, to let him fall into ecstasy. He wonders how many times Sans will make himself come before he gets home.

He grabs the eggs, deciding he'll make a quiche if Sans has been a good boy.

* * *

 Two. Hours. It's been two. Hours. He knows because he can actually see the alarm clock on the dresser now. Boss has been gone for two goddamn hours doing Gods know what and leaving Sans to slowly fall to insanity. 

He's pretty sure he's broken the headboard by now. He's afraid to look.

He's so close to just letting his hand slide between his legs. He's pretty sure whatever punishment Boss will dish out for disobeying him would hardly be worse than this. 

Sans doesn't really care if Papyrus punishes him, it's never anything severe (in fact, Sans secretly enjoys it), but he does care if he disappoints his Boss. He would do anything to make Papyrus proud, he wants to be a good boy. But,  _stars,_ is he making it hard. 

Maybe if he comes, he can work himself up again. Boss wouldn't know, would he--

The front door opened. 

Papyrus is home.  _Papyrus is home._

His pained whimpers quickly morph to desperate moans, and it takes everything in him to keep himself from screaming out.

* * *

He can hear him.  _Shit,_ he can  _smell_ him. The faint musk of Sans' magic had permeated through the house,  _as if he was in heat._ Suddenly, Papyrus' expert control of his magic disappears as he feels his pants grow that much tighter. 

He doesn't even take the groceries into the kitchen. He just tosses the bags onto the couch ( _it's not like anything needs to be refrigerated_ ) and he barely manages to keep himself contained enough to walk and not run. He pauses just outside his door; he knows he's going to lose it once the only barrier between him and his brother his removed. For once, he doesn't care.

 

The smell is so much stronger without the door in the way.

"b-boss~" _Shit._

Sans had his hands dug into the wooden headboard; his feet were flat on the bed, legs up and spread, and his back was arched in a way that made it look like his spine was about to snap in half. There's a wild, desperate look on his face, and Papyrus _knows_ he hadn't touched himself. 

Papyrus snaps back to reality and realizes Sans has been babbling desperately at him.

* * *

 "b-boss, please, boss, let me come,  _please-"_ he can't stop the words that are flowing out of his mouth, he can't stop himself from humping the air in a hopeless search of friction, and he's still afraid to let go of the headboard, afraid he'll push himself over the edge if he does and he's made it  _this far._

His eye sockets are locked on his brother as he strides across the room towards him. He's never needed him so much, never craved him so hard. 

Papyrus' hands are on him the second he gets close enough, pressing the vibe against his clit harder, and it's enough to make Sans scream. Papyrus leans over him, face inches above his own, so close that he can feel the warm puff of breath across his teeth. Sans' eyes widen and he feels himself relax under his Boss' hard gaze. He's calm in that moment.

Only in that moment.

Papyrus pushes three fingers into him, crooking them and finding his G-Spot with practiced precision. His toes curl and his eyes water, it takes everything in him not to come right then.

"You've been a good boy, haven't you?" Sans can only babble incorrectly in response. "You've waited so long, just like I told you to... You want to come so badly, don't you?" He manages to contort his face into something that says  _'no fucking shit.'_ Papyrus snorts. Sans bristles. "You're so wet, it's running down my wrist." and he twists his fingers inside him, the squelching noise that follows can only be described as sinfully lewd. 

"f-fuck, boss please, please i'm so-- i'm so close,  _stars,_ please," he's humping his brother's hand, every movement sending stars to his eyes, his release dangerously close, but he can't come without permission. Papyrus' grin twists into something sadistic. " _papyrus, please--_ " It's out of his mouth before he can stop it. Papyrus' expression falters at the sound of his name and  _oh shit, he fucked up--_

His fingers crook sharply, stabbing into Sans' G-Spot, something possessive blooming across his features. "Come."

He's coming before Papyrus even finishes the word, his entire body tensing, his back bowing as he's hit with what is quite possibly the hardest orgasm of his life. He's crying at the intensity of it, a scream tears from his throat that sounds something like a slur of 'Boss' and a profanity. 

It takes him a while to come down, the vibrator that is still pressed to him sending him into aftershocks. His breathing is hard and labored, and it takes him a few minutes to catch his breath. 

Papyrus is pressed hard against him, his head buried in his neck.

"Good boy,"

**Notes for the Chapter:**

> my god, I switched POVs way too many times, but I couldn't stick with one of them, I really couldn't.
> 
> I should really rename this to "good boy" with the amount of times I fucking use it. NOT ONCE IS THE WORD INSTRUCT IN THIS FIC

**Author's Note:**

> ahahahh i'm a fucking tease.


End file.
